[Coverage] Precise region termination with deferred regions

[vsk]

Summary

The current coverage implementation doesn't handle region termination
very precisely. Take for example an if statement with a return:

void f() {
  if (true) {
    return; // The `if' body's region is terminated here.
  }
  // This line gets the same coverage as the `if' condition.
}

If the function f is called, the line containing the comment will be
marked as having executed once, which is not correct. (Edit: To clarify,
I meant the second comment.)

The solution here is to create a deferred region after terminating a
region. The deferred region is completed once the start location of the
next statement is known, and is then pushed onto the region stack.
In the cases where it's not possible to complete a deferred region, it
can safely be dropped.

Example output (pre-patch):

deferred-regions-before.txt5 KBDownload

Example output (post-patch):

deferred-regions-after.txt5 KBDownload

Testing: lit test updates, a stage2 coverage-enabled build of clang

[arphaman]

This is awesome!

I noticed in the sample output that llvm-cov is now forced to print some new region markers because the terminator introduces a new region on the same line, e.g.

|// CHECK-LABEL: _Z10while_loopv:
   88|      1|void while_loop() {
   89|      1|  if (false)
   90|      1|    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
                  ^0    ^1  // Previously, llvm-cov didn't show region markers for this line
   91|      1|

Do you think this can be avoided? Should llvm-cov even try to avoid emitting the region markers? It seems to me that this situation affects just the command-line output of llvm-cov, and region highlighting in HTML won't be impacted by this.

[vsk]

In D35925#823978, @arphaman wrote:

This is awesome!

I noticed in the sample output that llvm-cov is now forced to print some new region markers because the terminator introduces a new region on the same line, e.g.

|// CHECK-LABEL: _Z10while_loopv:
   88|      1|void while_loop() {
   89|      1|  if (false)
   90|      1|    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
                  ^0    ^1  // Previously, llvm-cov didn't show region markers for this line
   91|      1|

Do you think this can be avoided? Should llvm-cov even try to avoid emitting the region markers? It seems to me that this situation affects just the command-line output of llvm-cov, and region highlighting in HTML won't be impacted by this.

Great question! The region highlighting for the html emitter matches exactly with the textual emitter's (edit: *should* match with D36020), so there is an impact. I think we can/should make two general improvements to llvm-cov to address the issue, which would be useful even without this patch. The first (as you brought up) is to stop emitting region markers for segments which start, but do not end, on one line. This fixes an existing annoyance with loops:

for (...; ...; ...) -> { <- This singular curly brace gets a region marker because the body's region starts here. That's a little distracting.

It would also suppress highlighting for deferred regions, removing a visual distraction.

The second improvement would be to to pick better line execution counts. In the sample output that you quoted, you see that the line with the return gets an execution count of 1. What's happening is that llvm-cov picks the maximum execution count from the regions on (or before) the line. The end result is a little weird, because we associate the line execution count with the first region on a line, and we know the "return" is never executed. I have a patch ready to fix this: it corrects a display issue in the existing llvm-cov test suite, and it helps even more with deferred regions enabled (edit: D36014).

[arphaman]

Thanks, it does make sense to update llvm-cov.

LGTM:

lib/CodeGen/CoverageMappingGen.cpp

554

Might be better to use && to avoid extra work.

561

You can use else if here.

[vsk]

Thanks for the review! I'll hold off on landing this until the llvm-cov changes are in, so that people don't hit the issue where unexpected line execution counts are displayed.

[vsk]

Committed in r310010

[vsk]

Reverted in r310154, because llvm-cov isn't doing a good job of displaying the new regions properly. I'll re-land this after llvm-cov is fixed.

lib/CodeGen/CoverageMappingGen.cpp

class SourceMappingRegion {
   Counter Count;
 
   /// \brief The region's starting location.
   Optional<SourceLocation> LocStart;
 
   /// \brief The region's ending location.
   Optional<SourceLocation> LocEnd;
 
+  /// Whether this region should be emitted after its parent is emitted.
+  bool DeferRegion;
+
 public:
   SourceMappingRegion(Counter Count, Optional<SourceLocation> LocStart,
-                      Optional<SourceLocation> LocEnd)
-      : Count(Count), LocStart(LocStart), LocEnd(LocEnd) {}
+                      Optional<SourceLocation> LocEnd, bool DeferRegion = false)
+      : Count(Count), LocStart(LocStart), LocEnd(LocEnd),
+        DeferRegion(DeferRegion) {}
 
   const Counter &getCounter() const { return Count; }
 
   void setCounter(Counter C) { Count = C; }
 
   bool hasStartLoc() const { return LocStart.hasValue(); }
 
   void setStartLoc(SourceLocation Loc) { LocStart = Loc; }
 
   SourceLocation getStartLoc() const {
     assert(LocStart && "Region has no start location");
     return *LocStart;
   }
 
   bool hasEndLoc() const { return LocEnd.hasValue(); }
 
   void setEndLoc(SourceLocation Loc) { LocEnd = Loc; }
 
   SourceLocation getEndLoc() const {
     assert(LocEnd && "Region has no end location");
     return *LocEnd;
   }
+
+  bool isDeferred() const { return DeferRegion; }
+
+  void setDeferred(bool Deferred) { DeferRegion = Deferred; }
 };
 
 /// Spelling locations for the start and end of a source region.
 struct SpellingRegion {
   /// The line where the region starts.
   unsigned LineStart;
 
   /// The column where the region starts.
struct CounterCoverageMappingBuilder
     : public CoverageMappingBuilder,
       public ConstStmtVisitor<CounterCoverageMappingBuilder> {
   /// \brief The map of statements to count values.
   llvm::DenseMap<const Stmt *, unsigned> &CounterMap;
 
   /// \brief A stack of currently live regions.
   std::vector<SourceMappingRegion> RegionStack;
 
+  /// The currently deferred region: its end location and count can be set once
+  /// its parent has been popped from the region stack.
+  Optional<SourceMappingRegion> DeferredRegion;
+
   CounterExpressionBuilder Builder;
 
   /// \brief A location in the most recently visited file or macro.
   ///
   /// This is used to adjust the active source regions appropriately when
   /// expressions cross file or macro boundaries.
   SourceLocation MostRecentLocation;
 
struct CounterCoverageMappingBuilder
   }
 
   /// \brief Push a region onto the stack.
   ///
   /// Returns the index on the stack where the region was pushed. This can be
   /// used with popRegions to exit a "scope", ending the region that was pushed.
   size_t pushRegion(Counter Count, Optional<SourceLocation> StartLoc = None,
                     Optional<SourceLocation> EndLoc = None) {
-    if (StartLoc)
+    if (StartLoc) {
       MostRecentLocation = *StartLoc;
+      completeDeferred(Count, MostRecentLocation);
+    }
     RegionStack.emplace_back(Count, StartLoc, EndLoc);
 
     return RegionStack.size() - 1;
   }
 
+  /// Complete any pending deferred region by setting its end location and
+  /// count, and then pushing it onto the region stack.
+  size_t completeDeferred(Counter Count, SourceLocation DeferredEndLoc) {
+    size_t Index = RegionStack.size();
+    if (!DeferredRegion)
+      return Index;
+
+    // Consume the pending region.
+    SourceMappingRegion DR = DeferredRegion.getValue();
+    DeferredRegion = None;
+
+    // If the region ends in an expansion, find the expansion site.
+    if (SM.getFileID(DeferredEndLoc) != SM.getMainFileID()) {
+      FileID StartFile = SM.getFileID(DR.getStartLoc());
+      if (isNestedIn(DeferredEndLoc, StartFile)) {
+        do {
+          DeferredEndLoc = getIncludeOrExpansionLoc(DeferredEndLoc);
+        } while (StartFile != SM.getFileID(DeferredEndLoc));
+      }
+    }
+
+    // The parent of this deferred region ends where the containing decl ends,
+    // so the region isn't useful.
+    if (DR.getStartLoc() == DeferredEndLoc)
+      return Index;
+
+    // If we're visiting statements in non-source order (e.g switch cases or
+    // a loop condition) we can't construct a sensible deferred region.
+    if (!SpellingRegion(SM, DR.getStartLoc(), DeferredEndLoc).isInSourceOrder())
+      return Index;
+
+    DR.setCounter(Count);
+    DR.setEndLoc(DeferredEndLoc);
+    handleFileExit(DeferredEndLoc);
+    RegionStack.push_back(DR);
+    return Index;
+  }
+
   /// \brief Pop regions from the stack into the function's list of regions.
   ///
   /// Adds all regions from \c ParentIndex to the top of the stack to the
   /// function's \c SourceRegions.
   void popRegions(size_t ParentIndex) {
     assert(RegionStack.size() >= ParentIndex && "parent not in stack");
+    bool ParentOfDeferredRegion = false;
     while (RegionStack.size() > ParentIndex) {
       SourceMappingRegion &Region = RegionStack.back();
       if (Region.hasStartLoc()) {
         SourceLocation StartLoc = Region.getStartLoc();
         SourceLocation EndLoc = Region.hasEndLoc()
                                     ? Region.getEndLoc()
                                     : RegionStack[ParentIndex].getEndLoc();
         while (!SM.isWrittenInSameFile(StartLoc, EndLoc)) {
while (RegionStack.size() > ParentIndex) {
         // If this region happens to span an entire expansion, we need to make
         // sure we don't overlap the parent region with it.
         if (StartLoc == getStartOfFileOrMacro(StartLoc) &&
             EndLoc == getEndOfFileOrMacro(EndLoc))
           MostRecentLocation = getIncludeOrExpansionLoc(EndLoc);
 
         assert(SM.isWrittenInSameFile(Region.getStartLoc(), EndLoc));
         SourceRegions.push_back(Region);
+
+        if (ParentOfDeferredRegion) {
+          ParentOfDeferredRegion = false;
+
+          // If there's an existing deferred region, keep the old one, because
+          // it means there are two consecutive returns (or a similar pattern).
+          if (!DeferredRegion.hasValue() &&
+              // File IDs aren't gathered within macro expansions, so it isn't
+              // useful to try and create a deferred region inside of one.
+              (SM.getFileID(EndLoc) == SM.getMainFileID()))
+            DeferredRegion =
+                SourceMappingRegion(Counter::getZero(), EndLoc, None);
+        }
+      } else if (Region.isDeferred()) {
+        assert(!ParentOfDeferredRegion && "Consecutive deferred regions");
+        ParentOfDeferredRegion = true;
       }
       RegionStack.pop_back();
     }
+    assert(!ParentOfDeferredRegion && "Deferred region with no parent");
   }
 
   /// \brief Return the currently active region.
   SourceMappingRegion &getRegion() {
     assert(!RegionStack.empty() && "statement has no region");
     return RegionStack.back();
   }
 
struct CounterCoverageMappingBuilder
   /// \brief Ensure that \c S is included in the current region.
   void extendRegion(const Stmt *S) {
     SourceMappingRegion &Region = getRegion();
     SourceLocation StartLoc = getStart(S);
 
     handleFileExit(StartLoc);
     if (!Region.hasStartLoc())
       Region.setStartLoc(StartLoc);
+
+    completeDeferred(Region.getCounter(), StartLoc);
   }
 
   /// \brief Mark \c S as a terminator, starting a zero region.
   void terminateRegion(const Stmt *S) {
     extendRegion(S);
     SourceMappingRegion &Region = getRegion();
     if (!Region.hasEndLoc())
       Region.setEndLoc(getEnd(S));
     pushRegion(Counter::getZero());
+    getRegion().setDeferred(true);
   }
 
   /// \brief Keep counts of breaks and continues inside loops.
   struct BreakContinue {
     Counter BreakCount;
     Counter ContinueCount;
   };
   SmallVector<BreakContinue, 8> BreakContinueStack;
 
   CounterCoverageMappingBuilder(
       CoverageMappingModuleGen &CVM,
       llvm::DenseMap<const Stmt *, unsigned> &CounterMap, SourceManager &SM,
       const LangOptions &LangOpts)
-      : CoverageMappingBuilder(CVM, SM, LangOpts), CounterMap(CounterMap) {}
+      : CoverageMappingBuilder(CVM, SM, LangOpts), CounterMap(CounterMap),
+        DeferredRegion(None) {}
 
   /// \brief Write the mapping data to the output stream
   void write(llvm::raw_ostream &OS) {
     llvm::SmallVector<unsigned, 8> VirtualFileMapping;
     gatherFileIDs(VirtualFileMapping);
     SourceRegionFilter Filter = emitExpansionRegions();
+    assert(!DeferredRegion && "Deferred region never completed");
     emitSourceRegions(Filter);
     gatherSkippedRegions();
 
     if (MappingRegions.empty())
       return;
 
     CoverageMappingWriter Writer(VirtualFileMapping, Builder.getExpressions(),
                                  MappingRegions);
     Writer.write(OS);
   }
 
   void VisitStmt(const Stmt *S) {
     if (S->getLocStart().isValid())
       extendRegion(S);
     for (const Stmt *Child : S->children())
       if (Child)
         this->Visit(Child);
     handleFileExit(getEnd(S));
   }
 
   void VisitDecl(const Decl *D) {
+    assert(!DeferredRegion && "Deferred region never completed");
+
     Stmt *Body = D->getBody();
 
     // Do not propagate region counts into system headers.
     if (Body && SM.isInSystemHeader(SM.getSpellingLoc(getStart(Body))))
       return;
 
-    propagateCounts(getRegionCounter(Body), Body);
+    Counter ExitCount = propagateCounts(getRegionCounter(Body), Body);
+    assert(RegionStack.empty() && "Regions entered but never exited");
+
+    // Complete any deferred regions introduced by the last statement in a decl.
+    popRegions(completeDeferred(ExitCount, getEnd(Body)));
   }
 
   void VisitReturnStmt(const ReturnStmt *S) {
     extendRegion(S);
     if (S->getRetValue())
       Visit(S->getRetValue());
     terminateRegion(S);
   }

test/CoverageMapping/deferred-region.cpp

+// RUN: %clang_cc1 -std=c++11 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -fexceptions -fcxx-exceptions -emit-llvm-only -triple %itanium_abi_triple -main-file-name deferred-region.cpp %s | FileCheck %s
+
+#define IF if
+#define STMT(S) S
+
+// CHECK-LABEL: _Z3fooi:
+void foo(int x) {
+  if (x == 0) {
+    return;
+  } // CHECK: [[@LINE]]:4 -> [[@LINE+2]]:2 = (#0 - #1)
+
+}
+
+// CHECK-NEXT: _Z4foooi:
+void fooo(int x) {
+  if (x == 0) {
+    return;
+  } // CHECK: [[@LINE]]:4 -> [[@LINE+2]]:3 = (#0 - #1)
+
+  if (x == 1) {
+    return;
+  } // CHECK: [[@LINE]]:4 -> [[@LINE+2]]:2 = ((#0 - #1) - #2)
+
+}
+
+// CHECK-LABEL: _Z3bazv:
+void baz() { // CHECK: [[@LINE]]:12 -> [[@LINE+2]]:2
+  return;    // CHECK-NOT: File
+}
+
+// CHECK-LABEL: _Z3bari:
+void bar(int x) {
+  IF (x)
+    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
+
+  IF (!x)
+    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = ((#0 - #1) - #2)
+
+  foo(x);
+}
+
+// CHECK-LABEL: _Z4quuxi:
+// Deferred regions are not emitted within macro expansions.
+void quux(int x) {
+  STMT(
+  if (x == 0)
+    return;)
+
+  // CHECK-NOT: [[@LINE-2]]:{{.*}} -> [[@LINE+2]]
+
+  if (x == 1)
+    STMT(return;)
+
+  // CHECK-NOT: [[@LINE-2]]:{{.*}} -> [[@LINE+3]]
+
+  STMT(
+  if (x == 2)
+    return;
+
+  // CHECK-NOT: [[@LINE-2]]:{{.*}} -> [[@LINE+2]]
+
+  if (x == 3)
+    return;
+  )
+}
+
+// CHECK-LABEL: _Z8for_loopv:
+void for_loop() {
+  if (false)
+    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
+
+  for (int i = 0; i < 10; ++i) {
+    if (i % 2 == 0)
+      continue; // CHECK: [[@LINE]]:15 -> [[@LINE+2]]:5 = (#2 - #3)
+
+    if (i % 5 == 0)
+      break; // CHECK: [[@LINE]]:12 -> [[@LINE+2]]:5 = ((#2 - #3) - #4)
+
+    int x = i; // CHECK: [[@LINE]]:5 -> [[@LINE+3]]:4 = ((#2 - #3) - #4)
+    return; // CHECK-NOT: [[@LINE]]:11 -> [[@LINE+2]]
+
+  }
+}
+
+struct Error {};
+
+// CHECK-LABEL: _Z10while_loopv:
+void while_loop() {
+  if (false)
+    return; // CHECK: [[@LINE]]:11 -> [[@LINE+2]]:3 = (#0 - #1)
+
+  int x = 0;
+  while (++x < 10) {
+    if (x == 1)
+      continue; // CHECK: [[@LINE]]:15 -> [[@LINE+2]]:5 = (#2 - #3)
+
+    while (++x < 4) {
+      if (x == 3)
+        break; // CHECK: [[@LINE]]:14 -> [[@LINE+2]]:7 = (#4 - #5)
+
+      while (++x < 5) {}
+    }
+
+    if (x == 0)
+      throw Error(); // CHECK: [[@LINE]]:20 -> [[@LINE+2]]:5 = ((#2 - #3) - #7)
+
+    while (++x < 9) {
+      if (x == 0)
+        break; // CHECK-NOT: [[@LINE]]:14 -> [[@LINE+2]]
+
+    }
+  }
+}
+
+// CHECK-LABEL: _Z5gotosv:
+void gotos() {
+  if (false)
+    goto out; // CHECK: [[@LINE]]:13 -> [[@LINE+2]]:3 = (#0 - #1)
+
+  return; // CHECK: [[@LINE]]:3 -> [[@LINE+4]]:2 = (#0 - #1)
+
+out:
+  return; // CHECK: [[@LINE]]:8 -> [[@LINE+1]]:2 = 0
+}
+
+int main() {
+  foo(0);
+  foo(1);
+  fooo(0);
+  fooo(1);
+  baz();
+  bar(0);
+  bar(1);
+  quux(0);
+  quux(1);
+  quux(2);
+  quux(3);
+  for_loop();
+  while_loop();
+  gotos();
+  return 0;
+}

test/CoverageMapping/label.cpp

 // RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name label.cpp %s | FileCheck %s
 
                              // CHECK: func
 void func() {                // CHECK-NEXT: File 0, [[@LINE]]:13 -> {{[0-9]+}}:2 = #0
   int i = 0;                 // CHECK-NEXT: File 0, [[@LINE+2]]:14 -> [[@LINE+2]]:20 = (#0 + #3)
                              // CHECK-NEXT: File 0, [[@LINE+1]]:22 -> [[@LINE+1]]:25 = #3
   for(i = 0; i < 10; ++i) {  // CHECK-NEXT: File 0, [[@LINE]]:27 -> [[@LINE+11]]:4 = #1
                              // CHECK-NEXT: File 0, [[@LINE+1]]:8 -> [[@LINE+1]]:13 = #1
     if(i < 5) {              // CHECK-NEXT: File 0, [[@LINE]]:15 -> [[@LINE+6]]:6 = #2
       {
         x:                   // CHECK-NEXT: File 0, [[@LINE]]:9 -> [[@LINE+4]]:6 = #3
           int j = 1;
       }
       int m = 2;
     } else
       goto x;                // CHECK-NEXT: File 0, [[@LINE]]:7 -> [[@LINE]]:13 = (#1 - #2)
-    int k = 3;               // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE+1]]:4 = #3
-  }
-  static int j = 0;          // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+4]]:2 = ((#0 + #3) - #1)
+    int k = 3;               // CHECK-NEXT: File 0, [[@LINE-1]]:13 -> [[@LINE]]:5 = #3
+  }                          // CHECK-NEXT: File 0, [[@LINE-1]]:5 -> [[@LINE]]:4 = #3
+  static int j = 0;          // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+5]]:2 = ((#0 + #3) - #1)
   ++j;
   if(j == 1)                 // CHECK-NEXT: File 0, [[@LINE]]:6 -> [[@LINE]]:12 = ((#0 + #3) - #1)
     goto x;                  // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:11 = #4
+                             // CHECK-NEXT: File 0, [[@LINE-1]]:11 -> [[@LINE+1]]:2 = (((#0 + #3) - #1) - #4)
 }
 
                              // CHECK-NEXT: test1
 void test1(int x) {          // CHECK-NEXT: File 0, [[@LINE]]:19 -> {{[0-9]+}}:2 = #0
   if(x == 0)                 // CHECK-NEXT: File 0, [[@LINE]]:6 -> [[@LINE]]:12 = #0
     goto a;                  // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:11 = #1
-  goto b;                    // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE]]:9 = (#0 - #1)
+                             // CHECK-NEXT: File 0, [[@LINE-1]]:11 -> [[@LINE+1]]:3 = (#0 - #1)
+  goto b;                    // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+5]]:2 = (#0 - #1)
+                             // CHECK-NEXT: File 0, [[@LINE-1]]:3 -> [[@LINE+4]]:2 = #3
 a:                           // CHECK-NEXT: File 0, [[@LINE]]:1 -> [[@LINE+3]]:2 = #2
 b:                           // CHECK-NEXT: File 0, [[@LINE]]:1 -> [[@LINE+2]]:2 = #3
   x = x + 1;
 }
 
                              // CHECK-NEXT: test2
 void test2(int x) {          // CHECK-NEXT: File 0, [[@LINE]]:19 -> {{[0-9]+}}:2 = #0
   if(x == 0)                 // CHECK-NEXT: File 0, [[@LINE]]:6 -> [[@LINE]]:12 = #0
     goto a;                  // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:11 = #1
-                             // CHECK-NEXT: File 0, [[@LINE+2]]:8 -> [[@LINE+2]]:25 = (#0 - #1)
+                             // CHECK-NEXT: File 0, [[@LINE-1]]:11 -> [[@LINE+3]]:8 = #0
+                             // CHECK-NEXT: File 0, [[@LINE+2]]:8 -> [[@LINE+3]]:11 = (#0 - #1)
                              // CHECK-NEXT: File 0, [[@LINE+1]]:11 -> [[@LINE+1]]:17 = (#0 - #1)
-  else if(x == 1) goto b;    // CHECK-NEXT: File 0, [[@LINE]]:19 -> [[@LINE]]:25 = #2
+  else if(x == 1)            // CHECK-NEXT: File 0, [[@LINE+1]]:5 -> [[@LINE+1]]:11 = #2
+    goto b;                  // CHECK-NEXT: File 0, [[@LINE]]:11 -> [[@LINE+1]]:1 = #3
 a:                           // CHECK-NEXT: File 0, [[@LINE]]:1 -> [[@LINE+3]]:2 = #3
 b:                           // CHECK-NEXT: File 0, [[@LINE]]:1 -> [[@LINE+2]]:2 = #4
   x = x + 1;
 }
 
                              // CHECK-NEXT: main
 int main() {                 // CHECK-NEXT: File 0, [[@LINE]]:12 -> {{[0-9]+}}:2 = #0
   int j = 0;
-  for(int i = 0; i < 10; ++i) { // CHECK: File 0, [[@LINE]]:31 -> [[@LINE+11]]:4 = #1
-  a:                         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+10]]:4 = #2
+  for(int i = 0; i < 10; ++i) { // CHECK: File 0, [[@LINE]]:31 -> [[@LINE+13]]:4 = #1
+  a:                         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+12]]:4 = #2
     if(i < 3)                // CHECK-NEXT: File 0, [[@LINE]]:8 -> [[@LINE]]:13 = #2
       goto e;                // CHECK-NEXT: File 0, [[@LINE]]:7 -> [[@LINE]]:13 = #3
-    goto c;                  // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:11 = (#2 - #3)
+                             // CHECK-NEXT: File 0, [[@LINE-1]]:13 -> [[@LINE+1]]:5 = (#2 - #3)
+    goto c;                  // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE+8]]:4 = (#2 - #3)
+
   b:                         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+6]]:4 = #4
     j = 2;
   c:                         // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+4]]:4 = #5
     j = 1;
                              // CHECK-NEXT: File 0, [[@LINE+1]]:3 -> [[@LINE+2]]:4 = #6
   e: f: ;                    // CHECK-NEXT: File 0, [[@LINE]]:6 -> [[@LINE+1]]:4 = #7
   }
   func();                    // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:2 = ((#0 + #7) - #1)
   test1(0);
   test2(2);
 }

test/CoverageMapping/moremacros.c

int main(int argc, const char *argv[]) {
   if (!argc) {} // CHECK-NEXT: File 0, [[@LINE]]:14 -> [[@LINE]]:16 = #1
 
   // CHECK-NEXT: File 0, [[@LINE+3]]:7 -> [[@LINE+3]]:12 = #0
   // CHECK-NEXT: Expansion,File 0, [[@LINE+2]]:14 -> [[@LINE+2]]:19 = #2
   // CHECK-NEXT: File 0, [[@LINE+1]]:19 -> [[@LINE+4]]:8 = #2
   if (!argc) LBRAC
     return 0;
   // CHECK-NEXT: Expansion,File 0, [[@LINE+1]]:3 -> [[@LINE+1]]:8 = #2
-  RBRAC
+  RBRAC // CHECK-NEXT: [[@LINE]]:8 -> [[@LINE+6]]:3 = (#0 - #2)
 
   // CHECK-NEXT: File 0, [[@LINE+4]]:3 -> [[@LINE+15]]:2 = (#0 - #2)
   // CHECK-NEXT: File 0, [[@LINE+3]]:7 -> [[@LINE+3]]:12 = (#0 - #2)
   // CHECK-NEXT: Expansion,File 0, [[@LINE+2]]:14 -> [[@LINE+2]]:19 = #3
   // CHECK-NEXT: File 0, [[@LINE+1]]:19 -> [[@LINE+3]]:4 = #3
   if (!argc) LBRAC
     return 0;
-  }
+  } // CHECK-NEXT: [[@LINE]]:4 -> [[@LINE+5]]:3 = ((#0 - #2) - #3)
 
   // CHECK-NEXT: File 0, [[@LINE+3]]:3 -> [[@LINE+7]]:2 = ((#0 - #2) - #3)
   // CHECK-NEXT: File 0, [[@LINE+2]]:7 -> [[@LINE+2]]:12 = ((#0 - #2) - #3)
   // CHECK-NEXT: File 0, [[@LINE+1]]:14 -> [[@LINE+4]]:8 = #4
   if (!argc) {
     return 0;
   // CHECK-NEXT: Expansion,File 0, [[@LINE+1]]:3 -> [[@LINE+1]]:8 = #4
-  RBRAC
+  RBRAC // CHECK-NEXT: [[@LINE]]:8 -> [[@LINE+1]]:2 = (((#0 - #2) - #3) - #4)
 }
 
 // CHECK-NEXT: File 1, 3:15 -> 3:16 = #2
 // CHECK-NEXT: File 2, 4:15 -> 4:16 = #2
 // CHECK-NEXT: File 3, 3:15 -> 3:16 = #3
 // CHECK-NEXT: File 4, 4:15 -> 4:16 = #4

test/CoverageMapping/return.c

 // RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name return.c %s | FileCheck %s
 
                                 // CHECK: func
 void func() {                   // CHECK: File 0, [[@LINE]]:13 -> [[@LINE+3]]:2 = #0
   return;
   int i = 0;                    // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:2 = 0
 }
 
                                 // CHECK-NEXT: func2
 void func2() {                  // CHECK-NEXT: File 0, [[@LINE]]:14 -> {{[0-9]+}}:2 = #0
                                 // CHECK-NEXT: File 0, [[@LINE+2]]:18 -> [[@LINE+2]]:24 = ((#0 + #1) - #2)
                                 // CHECK-NEXT: File 0, [[@LINE+1]]:26 -> [[@LINE+1]]:29 = (#1 - #2)
   for(int i = 0; i < 10; ++i) { // CHECK-NEXT: File 0, [[@LINE]]:31 -> {{[0-9]+}}:4 = #1
                                 // CHECK-NEXT: File 0, [[@LINE+1]]:8 -> [[@LINE+1]]:13 = #1
     if(i > 2) {                 // CHECK-NEXT: File 0, [[@LINE]]:15 -> [[@LINE+2]]:6 = #2
-      return;
+      return;                   // CHECK-NEXT: File 0, [[@LINE+1]]:6 -> [[@LINE+3]]:5 = (#1 - #2)
     }                           // CHECK-NEXT: File 0, [[@LINE+2]]:5 -> {{[0-9]+}}:4 = (#1 - #2)
                                 // CHECK-NEXT: File 0, [[@LINE+1]]:8 -> [[@LINE+1]]:14 = (#1 - #2)
     if(i == 3) {                // CHECK-NEXT: File 0, [[@LINE]]:16 -> [[@LINE+2]]:6 = #3
       int j = 1;
     } else {                    // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+2]]:6 = ((#1 - #2) - #3)
       int j = 2;
     }
   }

test/CoverageMapping/switch.cpp

 // RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -std=c++1z -triple %itanium_abi_triple -main-file-name switch.cpp %s | FileCheck %s
 
                     // CHECK: foo
 void foo(int i) {   // CHECK-NEXT: File 0, [[@LINE]]:17 -> [[@LINE+8]]:2 = #0
   switch(i) {
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:10 = #2
     return;
   case 2:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #3
-    break;
+    break;          // CHECK-NEXT: File 0, [[@LINE]]:10 -> [[@LINE+2]]:3 = #1
   }
   int x = 0;        // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:2 = #1
 }
 
 int nop() { return 0; }
 
                     // CHECK: bar
 void bar(int i) {   // CHECK-NEXT: File 0, [[@LINE]]:17 -> [[@LINE+20]]:2 = #0
int main() {        // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+35]]:2 = #0
   switch(i) {
   case 0:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+7]]:10 = #2
     i = 1;
     break;
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:10 = #3
     i = 2;
     break;
   default:          // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = #4
-    break;
+    break;          // CHECK-NEXT: File 0, [[@LINE]]:10 -> [[@LINE+2]]:3 = #1
   }
   switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+23]]:2 = #1
   case 0:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+6]]:10 = #6
     i = 1;
     break;
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:10 = #7
     i = 2;
   default:          // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:10 = (#7 + #8)
-    break;
+    break;          // CHECK-NEXT: File 0, [[@LINE]]:10 -> [[@LINE+3]]:3 = #5
   }
 
   switch(i) {       // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+13]]:2 = #5
   case 1:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+5]]:11 = #10
   case 2:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+4]]:11 = (#10 + #11)
     i = 11;
   case 3:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+2]]:11 = ((#10 + #11) + #12)
   case 4:           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:11 = (((#10 + #11) + #12) + #13)
     i = 99;
   }
 
   foo(1);           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+3]]:11 = #9
   bar(1);
   baz();
   return 0;
 }

test/CoverageMapping/switchmacro.c

 // RUN: %clang_cc1 -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name switchmacro.c %s | FileCheck %s
 
 #define FOO(x) (void)x
 
 // CHECK: foo
 int foo(int i) { // CHECK-NEXT: File 0, [[@LINE]]:16 -> {{[0-9]+}}:2 = #0
   switch (i) {
   default:       // CHECK-NEXT: File 0, [[@LINE]]:3 -> {{[0-9]+}}:11 = #2
     if (i == 1)  // CHECK-NEXT: File 0, [[@LINE]]:9 -> [[@LINE]]:15 = #2
       return 0;  // CHECK-NEXT: File 0, [[@LINE]]:7 -> [[@LINE]]:15 = #3
+                 // CHECK-NEXT: File 0, [[@LINE-1]]:15 -> [[@LINE+3]]:5 = (#2 - #3)
     // CHECK-NEXT: Expansion,File 0, [[@LINE+2]]:5 -> [[@LINE+2]]:8 = (#2 - #3) (Expanded file = 1)
     // CHECK-NEXT: File 0, [[@LINE+1]]:8 -> {{[0-9]+}}:11 = (#2 - #3)
     FOO(1);
   case 0:        // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE+1]]:13 = ((#2 + #4) - #3)
     return 2;
 
   // CHECK-NEXT: Expansion,File 0, [[@LINE+2]]:3 -> [[@LINE+2]]:6 = 0
   // CHECK-NEXT: File 0, [[@LINE+1]]:6 -> {{[0-9]+}}:11 = 0

test/CoverageMapping/trycatch.cpp

 void func(int i) {                    // CHECK-NEXT: File 0, [[@LINE]]:18 -> {{[0-9]+}}:2 = #0
                                       // CHECK-NEXT: File 0, [[@LINE+1]]:6 -> [[@LINE+1]]:11 = #0
   if(i % 2) {                         // CHECK-NEXT: File 0, [[@LINE]]:13 -> [[@LINE+4]]:4 = #1
     throw Error();
     int j = 0;                        // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE+2]]:4 = 0
                                       // CHECK-NEXT: File 0, [[@LINE+1]]:10 -> [[@LINE+2]]:27 = (#0 - #1)
   } else if(i == 8)                   // CHECK-NEXT: File 0, [[@LINE]]:13 -> [[@LINE]]:19 = (#0 - #1)
     throw ImportantError();           // CHECK-NEXT: File 0, [[@LINE]]:5 -> [[@LINE]]:27 = #2
-}
+}                                     // CHECK-NEXT: File 0, [[@LINE-1]]:27 -> [[@LINE]]:2 = ((#0 - #1) - #2)
 
                                       // CHECK-NEXT: main
 int main() {                          // CHECK-NEXT: File 0, [[@LINE]]:12 -> [[@LINE+13]]:2 = #0
   int j = 1;
   try {                               // CHECK-NEXT: File 0, [[@LINE]]:7 -> [[@LINE+2]]:4 = #0
     func(j);
   } catch(const Error &e) {           // CHECK-NEXT: File 0, [[@LINE]]:27 -> [[@LINE+2]]:4 = #2
     j = 1;
   } catch(const ImportantError &e) {  // CHECK-NEXT: File 0, [[@LINE]]:36 -> [[@LINE+2]]:4 = #3
     j = 11;
   }
   catch(const Warning &w) {           // CHECK-NEXT: File 0, [[@LINE]]:27 -> [[@LINE+2]]:4 = #4
     j = 0;
   }
   return 0;                           // CHECK-NEXT: File 0, [[@LINE]]:3 -> [[@LINE]]:11 = #1
 }